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A small tile of glass, marble, or other substance, of various colors, used in making ornamental patterns in mosaic pavements. Fairholt.

A material used for grinding, as emery, sand, powdered glass, etc.

cave, of substances having different refractive and dispersive powers, as crown and flint glass, with the curvatures so adjusted that the chromatic aberration produced by the one is corrected by other, and light emerges from the compound lens undecomposed. -- Achromatic prism. See Prism. -- Achromatic telescope, or m…

Applied to a kind of variegated glass beads of ancient manufacture; as, aggry beads are found in Ashantee and Fantee in Africa.

An apparatus formerly used in distillation, usually made of glass or metal. It has mostly given place to the retort and worm still. Used also metaphorically. The alembic of a great poet's imagination. Brimley.

is the sil atticum of the ancients. Under the name of Indian red it is used for polishing glass and silver.

A picture taken on a place of prepared glass, in which the lights are represented in silver, and the shades are produced by a dark background visible through the unsilvered portions of the glass.

hous; esp. a state of being without crystallization even in the minutest particles, as in glass, opal, etc.

Springing back, as the bottom of an anaclastic glass. Anaclastic glass, a glass or phial, shaped like an inverted funnel, and with a very thin convex bottom. By sucking out a little air, the bottom springs into a concave form with a smart crack; and by breathing or blowing gently into the orifice, the bottom, with a li…

Glass gall or sandiver.

To subject to great heat, and then cool slowly, as glass, cast iron, steel, or other metal, for the purpose of rendering it less brittle; to temper; to toughen.

The process used to render glass, iron, etc., less brittle, performed by allowing them to cool very gradually from a high heat.

A mineral of the feldspar family, commonly occurring in small glassy crystals, also a constituent of some igneous rocks. It is a lime feldspar. See Feldspar.

A device, one form of which consists of a scratched deposit of silver on glass, used in connection with the receiving apparatus for reading wireless signals. The electric waves falling on this contrivance increase its resistance several times. The anticoherer can be used in conjunction with a telephone.…

The diameter of the exposed part of the object glass of a telescope or other optical instrument; as, a telescope of four-inch aperture.

two such foci; and it is by taking advantage of this fact that the best aplanatic object glasses of microscopes are constructed.

An artificial pond, or a globe or tank (usually with glass sides), in which living specimens of aquatic animals or plants are kept.

A lamp with a circular hollow wick and glass chimney which allow a current of air both inside and outside of the flame. Argand burner, a burner for an Argand lamp, or a gas burner in which the principle of that lamp is applied.

Pertaining to, consisting of, or containing, arsenic; as, arsenious powder or glass.

A furnace or oven for fritting materials for glass making.